Piper H M, Spahr R, Schweickhardt C, Hunneman D H, Probst I
Biochim Biophys Acta. 1986 Oct 1;883(3):531-41. doi: 10.1016/0304-4165(86)90294-1.
In Ca-tolerant adult cardiomyocytes the contribution of endogenous substrates (glycogen, tri- and diacylglycerol) to oxidative substrate metabolism was investigated. After 4 h in culture medium (M 199 plus 4% fetal calf serum) the cellular triacylglycerol content is 3.6-fold higher than in fresh myocardium and reflects the free fatty acid composition of the medium. When triacylglycerol is degraded, all long-chain fatty acids are hydrolysed at equal rates. In these quiescent cells, the activity of pyruvate dehydrogenase is low (10% of full activity, in Tyrode solution with 5 mM glucose). Up to 30% of full pyruvate dehydrogenase activity, the contribution of non-lipid substrates (glycogen, glucose, lactate and pyruvate) to oxidative energy production is correlated to pyruvate dehydrogenase activity. At 5 mM medium concentration, glucose, lactate and pyruvate share in energy production the proportions of 15, 36 and 50%, whereas endogenous lipolysis accounts for 78, 61 and 46%. It is concluded that these quiescent cardiomyocytes represent cardiac metabolism in a basal state in which the preference for fatty acids, especially from endogenous lipids, is very pronounced. The utilization of endogenous substrates therefore has to be considered in all studies investigating the oxidative metabolism of these isolated cells.
在耐钙的成年心肌细胞中，研究了内源性底物（糖原、三酰甘油和二酰甘油）对氧化底物代谢的贡献。在培养基（M199加4%胎牛血清）中培养4小时后，细胞内三酰甘油含量比新鲜心肌高3.6倍，反映了培养基中的游离脂肪酸组成。当三酰甘油降解时，所有长链脂肪酸以相同速率水解。在这些静止细胞中，丙酮酸脱氢酶的活性较低（在含5 mM葡萄糖的台氏液中为最大活性的10%）。在丙酮酸脱氢酶活性达到最大活性的30%之前，非脂质底物（糖原、葡萄糖、乳酸和丙酮酸）对氧化能量产生的贡献与丙酮酸脱氢酶活性相关。在培养基浓度为5 mM时，葡萄糖、乳酸和丙酮酸在能量产生中的比例分别为15%、36%和50%，而内源性脂解分别占78%、61%和46%。得出的结论是，这些静止的心肌细胞代表了基础状态下的心脏代谢，其中对脂肪酸，尤其是内源性脂质的脂肪酸的偏好非常明显。因此，在所有研究这些分离细胞氧化代谢的研究中，都必须考虑内源性底物的利用。
